1. Field of the Invention
The present invention relates to drum type washing machines, and more particularly, to a drum type washing machine and dryer and a method for automatic drying by using the same, in which a temperature sensor is provided to a duct therein for determining a dryness by using a temperature change of an inside of the duct.
2. Discussion of the Related Art
In general, the drum type washing machine, performing washing by using friction between a drum rotated by driving force from a motor and laundry in a state detergent, washing water, and the laundry are introduced therein, gives less damage to the laundry, has less entangling of the laundry, and can provide a washing effect of pounding and rubbing the laundry.
Keeping pace with the trend of improving functions of, and manufacturing high quality drum type washing machines, it is a trend that demands on the drum type washing machine and dryer are also increasing, which enables, not only washing and spinning, but also drying of the laundry.
The drum type washing machine and dryer forcibly draws and heat external air by fan and heater mounted on an outside of a tub, and blows heated high temperature air toward an inside of the tub, to dry the laundry.
In general, a related art drum type washing machine performs drying by a manual drying method in which a user selects a desired drying course, and sets an appropriate drying time period according to an amount of the laundry, and makes a drying cycle performed, wherein, due to failure in performing an accurate drying cycle, to dry the laundry imperfectly, or excessively, a user desired drying state can not be met.
Referring to FIG. 1A, in order to solve such a problem, a device is developed, in which temperatures of an inside of the tub, and an inside of the duct are sensed by using a temperature sensor in the tub for sensing the inside of the tub, and a duct temperature sensor in the duct, estimates a laundry amount according to a temperature difference of the tub temperature and the duct temperature automatically, and sets a drying time period according to the laundry amount estimated thus, for performing the drying cycle.
For an example, referring to FIG. 1B, if a difference between the temperature (‘a duct temperature’) measured with the duct temperature sensor in the duct and the temperature (‘a tub temperature’) measured with the temperature sensor in the tub is greater than a certain value K in a first step, the laundry amount is determined to be ordinary (2˜3 kg), if the difference of the duct temperature and the tub temperature is smaller than the certain value K in the first step, and the difference of temperatures is reduced from a maximum value by a certain level in a second step, the laundry amount is determined to be small (500 g˜1 kg), and if the difference of temperatures is smaller than the certain value in the first, and second steps, to fail to determined the laundry amount, the laundry amount is determined to be great (3.5˜4.5 kg) in which above steps are terminated after a certain time period, for performing the drying cycle.
However, above determination of laundry amount by using the difference of the tub temperature and the duct temperature has difficulty in sub-division of a range of the laundry amount required for determination of an accurate laundry amount, and, it is known from experience that above determination has no consistency throughout an entire range of laundry amount, making that it is difficult to perform the drying cycle according to above determination.
Particularly, when the laundry amount is small, the laundry suffers from damage caused by excessive drying.
Moreover, above related art drying cycle performing method has a difficulty in making accurate drying for entire range of laundry amount, and excessively large range of drying time period divisions, unable to apply to a large sized drum type washing machine greater than 10 Kg.
Moreover, because the related art automatic drying cycle performing method does not take a position of the temperature sensor in the tub. a deviation of the temperature sensor itself, a deviation of a structure of the duct, a deviation of a beating performance into account, test pieces show different temperature characteristics.
In such cases, it is not reasonable to apply one algorithm to all washing machines.
The deviation of every test piece leads application of an automatic drying algorithm for performing accurate drying the consumers desire difficult.